diff --git a/commands.go b/commands.go
index 1fc22aa..6068bab 100644
--- a/commands.go
+++ b/commands.go
@@ -196,7 +196,7 @@ type Sort struct {
 func (c *Client) Sort(key string, sort Sort) *StringSliceCmd {
 	args := []string{"SORT", key}
 	if sort.By != "" {
-		args = append(args, sort.By)
+		args = append(args, "BY", sort.By)
 	}
 	if sort.Offset != 0 || sort.Count != 0 {
 		args = append(args, "LIMIT", formatFloat(sort.Offset), formatFloat(sort.Count))
diff --git a/redis_test.go b/redis_test.go
index 4ce3eb2..49f84d0 100644
--- a/redis_test.go
+++ b/redis_test.go
@@ -786,6 +786,29 @@ func (t *RedisTest) TestCmdKeysSort(c *C) {
 	c.Assert(sort.Val(), DeepEquals, []string{"1", "2"})
 }
 
+func (t *RedisTest) TestCmdKeysSortBy(c *C) {
+	lPush := t.client.LPush("list", "1")
+	c.Assert(lPush.Err(), IsNil)
+	c.Assert(lPush.Val(), Equals, int64(1))
+	lPush = t.client.LPush("list", "3")
+	c.Assert(lPush.Err(), IsNil)
+	c.Assert(lPush.Val(), Equals, int64(2))
+	lPush = t.client.LPush("list", "2")
+	c.Assert(lPush.Err(), IsNil)
+	c.Assert(lPush.Val(), Equals, int64(3))
+
+	set := t.client.Set("weight_1", "5")
+	c.Assert(set.Err(), IsNil)
+	set = t.client.Set("weight_2", "2")
+	c.Assert(set.Err(), IsNil)
+	set = t.client.Set("weight_3", "8")
+	c.Assert(set.Err(), IsNil)
+
+	sort := t.client.Sort("list", redis.Sort{Offset: 0, Count: 2, Order: "ASC", By: "weight_*"})
+	c.Assert(sort.Err(), IsNil)
+	c.Assert(sort.Val(), DeepEquals, []string{"2", "1"})
+}
+
 func (t *RedisTest) TestCmdKeysTTL(c *C) {
 	ttl := t.client.TTL("key")
 	c.Assert(ttl.Err(), IsNil)